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Fixes for Legacy GL/GLES #1380

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Merged
barbeque-squared merged 3 commits into from
Aug 10, 2026
Merged

Fixes for Legacy GL/GLES #1380

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7f4dde7
GLES2: Require GL_OES_element_index_uint extension
complexlogic Aug 4, 2026
c0abd48
Use GL_LUMINANCE for legacy drivers that don't support GL_RED
complexlogic Aug 4, 2026
dea1c90
Define GL_LUMINANCE in URenderer_OpenGL
complexlogic Aug 9, 2026
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18 changes: 16 additions & 2 deletions src/base/URenderer_OpenGL.pas
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Original file line number Diff line number Diff line change
Expand Up @@ -77,6 +77,7 @@ TRenderer_OpenGLBase = class(TRenderer)
SupportsVAO: boolean;
SupportsFBO: boolean;
SupportsMappedBuffer: boolean;
GlyphTextureFormat: GLint;

MappedBuffer: PGLfloat; // OpenGL 2.0 doesn't support mapped buffers, so we manage it ourself.

Expand Down Expand Up @@ -284,6 +285,7 @@ implementation
MAX_QUADS = (VBO_SIZE div QUAD_STRIDE_BYTES); // Number of quads that can be stored in the VBO
EBO_INDICES = MAX_QUADS * 6; // 2 triangles, 6 total vertices per quad
EBO_SIZE = EBO_INDICES * SizeOf(GLuint);
GL_LUMINANCE = $1909;

type
TTexture_OpenGL = class(TTexture)
Expand Down Expand Up @@ -1523,7 +1525,7 @@ function TRenderer_OpenGLBase.LoadTexture(Data: PByte; W, H: integer; const Iden
// store this in the red channel, and later assign it to alpha in the fragment shader
function TRenderer_OpenGLBase.LoadGlyph(Data: PByte; W, H: integer): TTexture;
begin
Result := TTexture_OpenGL.Create(Data, W, H, PATH_NONE, GL_RED, 1, GL_CLAMP_TO_EDGE);
Result := TTexture_OpenGL.Create(Data, W, H, PATH_NONE, GlyphTextureFormat, 1, GL_CLAMP_TO_EDGE);
{$IFDEF DEBUG_MODE}
RaiseExceptionIfError;
{$ENDIF};
Expand Down Expand Up @@ -1768,6 +1770,7 @@ procedure TRenderer_OpenGL3.CheckVersion();
SupportsVAO := true;
SupportsFBO := true;
SupportsMappedBuffer := true;
GlyphTextureFormat := GL_RED;
if ((MajorVersion > 3) or ((MajorVersion = 3) and (MinorVersion >= 3))) then
fSupportsProjectM := true;
end;
Expand Down Expand Up @@ -1818,6 +1821,8 @@ procedure TRenderer_OpenGLES.CheckVersion();
var
Extensions: string;
GL_OES_vertex_array_object: boolean;
GL_OES_element_index_uint: boolean;
GL_EXT_texture_rg: boolean;
begin
if (MajorVersion < 2) then
raise Exception.Create('Could not initialize OpenGL ES 2.0 or later');
Expand All @@ -1827,14 +1832,22 @@ procedure TRenderer_OpenGLES.CheckVersion();
SupportsVAO := true;
fSupportsProjectM := true;
SupportsMappedBuffer := true;
GlyphTextureFormat := GL_RED;
end
else
begin
Extensions := Int_GetExtensionString;
GL_OES_element_index_uint := Int_CheckExtension(Extensions, 'GL_OES_element_index_uint');
if (not GL_OES_element_index_uint) then
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raise Exception.Create('OpenGL ES driver does not support the required GL_OES_element_index_uint extension');
GL_OES_vertex_array_object := Int_CheckExtension(Extensions, 'GL_OES_vertex_array_object');
if (GL_OES_vertex_array_object) then
SupportsVAO := true;

GL_EXT_texture_rg := Int_CheckExtension(Extensions, 'GL_EXT_texture_rg');
if (GL_EXT_texture_rg) then
GlyphTextureFormat := GL_RED
else
GlyphTextureFormat := GL_LUMINANCE;
end;
SupportsFBO := true;
end;
Expand Down Expand Up @@ -1887,6 +1900,7 @@ procedure TRenderer_OpenGL2.CheckVersion();
SupportsMappedBuffer := true;
fSupportsProjectM := false;
SupportsFBO := false;
GlyphTextureFormat := GL_LUMINANCE;
end;

procedure TRenderer_OpenGL2.GetShaderSource(out MainVertex, MainFragment, TextFragment, LineStripVertex, LineStripFragment: string);
Expand Down
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